Damage of glasses on the transportation means, particularly front glasses of cars, usually occurs due to hitting of a small stone or similar small and hard thing to glass surface. In the point of collision, a part of the glass surface is chipped off and the damage may be of different depth and width. Very often, the damage shape is conical in which other radial cracks originate. Replacement of the glass is expensive and therefore, a wide range of methods and appliances for repairs of damaged windscreens of cars in situ without necessity of replacing of the windscreen glass.
The patent document U.S. Pat. No. 3,841,932 describes the method and appliance for repair of local conical damage where the glass is heated in the point of damage by a lamp and semi-circular plastic container is stuck to the point of damage with repair liquid, particularly polymerizable glue or resin. After running of the liquid to the point of damage, the chipped off glass is filled in and the repair point is then hardened. A disadvantage of this method and appliance is that the repair liquid does not run reliably to full crack area including potential radial cracks.
Another patent document U.S. Pat. No. 4,385,015 describes an appliance for repair of resisting glasses such as windscreens of cars. The appliance consists of two parts: a shell under which underpressure is generated and a cylinder fixed in the centre of the shell above glass damage. There is a hole in the cylinder side to expand underpressure to the point of repair and there is a piston above the compartment. Prior to introduction of underpressure, repair liquid is poured to the damage point. Underpressure acts to remove air bubbles from the repair liquid and the piston is then pressed. By pushing the piston on the liquid only after hole in the cylinder wall, the liquid is forced to fill in the compartment in the crack where it would not run spontaneously. Disadvantage of the invention is that by introducing of underpressure after application of the repair liquid, moisture is not removed from the point of damage and releasing gas produces new bubbles in the liquid.
Possibility for fixing to glass using underpressure throughout the period time has been mentioned in the patent document U.S. Pat. No. 4,776,780. This is an appliance with a diaphragm in its lower pedestal and the diaphragm is specially shaped so that it creates several separated spaces. Underpressure is achieved to fix the appliance to the glass in created in the peripheral inner compartment along the diaphragm circumference. This attachment to the glass is then fixed by an element to capture underpressure in the compartment. Another compartment is created under the diaphragm above the point of repair. Underpressure does not act in this compartment but the one is connected to the piston under which glue is poured and pushed into the glass break point. A disadvantage is that the glass break point is not free of all air, resisting to the glue and therefore, the glue runs to the glass break point with difficulties.
Improved solution of previous methods and appliances for repair of glass damage is the subject of the patented document U.S. Pat. No. 6,589,036. The patent describes an appliance consisting of a plastic body to which sealing collar on external circumference of a lid is attached using a matrix. The plastic body has a borehole for piston and borehole for installation of closed capsule with repair liquid (glue). The lid is fitted with a seal that divides the compartment under the sealing collar into the repair compartment above the break point and fixing compartment. The device is attached above the break point and fixed to the glass by partial underpressure from air pump in the fixing compartment around the repair compartment that is has shape of sealed circle ring. This partial underpressure is then released by disc valve to the separated repair compartment as well. The disc valve is then closed and increased underpressure by ejecting the piston is created in the repair compartment. After unlocking, the glue capsules are broken and the glue flows to the break point due to increased underpressure. Then, the underpressure is balanced and using the piston, pressure is developed on the glue in the repair point to allow running of the glue to all cracks and corners of the break point. A disadvantage of this solution is that partial even increased underpressure and pressure developed over the glue acts on the disc valve in the opening direction and thereby, glue leaks through the disc valve and pressure drops around the repair point. The glue is to a certain extent evacuated inside the appliance and air bubbles are present in the glue. The appliance gets dirty, must be cleaned and the repaired point shows optically undesirable defects in the form of microscopic bubbles. It is also disadvantageous when the glue is dosed by capsules of which volume is not always corresponding to the extent of glass damage. Design of the appliance is complex and its disadvantages are based mainly on the fact it contains the first means for normal pressure as well as second means for increased underpressure and during pressure changes, the glue and pressure leaks occur.
The patent document U.S. Pat. No. 6,485,281 describes an appliance for glass repair, consisting of a piston with a nozzle, from which the glue is pressed into the crack and at the same time, the nozzle is placed in an adapter that produces underpressure around the nozzle orifice. This ensures that no air blocks the glue flow during repair. A disadvantage of this solution is that during repair the glue is partially removed by pressure, makes tubes to the vacuum pump clogged and glue consumption increases.
The British patent document GB 2 469 527 presents an appliance mounted on a holder fixed on glass. The appliance consists of a piston with glue bin attached through the wall. The piston is lifted up and underpressure is generated. The glue is left flowing to the point of destination and then, the piston produces pressure to push the glue to the break point. A disadvantage of this solution is that the pressure generated is limited by the piston volume. When the piston is lifted up again, the glue would be removed from the break point.
The purpose of this invention is to produce an appliance, which would eliminate the drawbacks of existing solutions, particularly according to U.S. Pat. No. 6,589,036 patent. Design of the appliance must be to avoid flowing of glue inside the appliance and reducing underpressure/pressure during repair. Another purpose of the invention is simplified handling of the appliance, particularly as far as the glue application is concerned. In addition, the appliance should be universally applicable for different glue types, i.e. not limited to certain shape or size of capsules or glue types available on the market in these capsules only.